Active-matrix driven display devices such as liquid-crystal display devices or organic EL display devices use a thin-film semiconductor device (hereafter referred to simply as “semiconductor device”) called a thin-film transistor (TFT).
In a display device, a TFT is used as a switching element for selecting a pixel or as a driving transistor which drives a pixel.
Such a TFT has a configuration in which a source electrode and a drain electrode, a semiconductor layer (channel layer), and a gate electrode are sequentially stacked on a substrate. A silicon semiconductor in the form of a thin film is typically used for the channel layer used in the TFT (see, Patent Literature (PTL) 1 for example).
Such silicon semiconductor films are broadly divided into non-crystalline silicon films (amorphous silicon: a-SI) and silicon films having crystallinity (crystalline silicon films). Crystalline silicon films are further classified into polycrystalline silicon films, microcrystalline silicon films, monocrystalline silicon films, and so on.
Non-crystalline silicon films can be manufactured evenly on a large-area substrate at relatively low temperatures using a chemical vapor deposition method (CVD method), and are thus presently the most commonly used as channel layers for large-screen liquid-crystal display devices. However, since characteristics, such as carrier mobility (on-characteristics), of non-crystalline silicon films are inferior to those of crystalline silicon films, the realization of TFTs having a crystalline silicon film as a channel layer is eagerly awaited in order to realize a display with enhanced high-speed driving and high-definition.
Conventionally, a method (direct CVD method) of directly forming a crystalline silicon film during film-forming using chemical vapor deposition (CVD) is available as a method of forming a crystalline silicon film (see PTL 2 for example). Alternatively, there is also a method in which a non-crystalline silicon film is formed before hand and then crystallized by applying thermal or light energy (see PTL 3 for example). As a method of applying light energy for crystallization, there is a method (laser annealing method) of locally applying a short burst of energy such as an excimer laser, a solid-state laser, a semiconductor laser, and so on. Furthermore, as methods of applying thermal energy, there are, for example, thermal annealing methods such as rapid thermal annealing (RTA) and rapid thermal processing (RTP), or thermal annealing methods which make use of catalytic action of nickel (Ni), and so on.